Electronically controlled dispenser for dispensing flexible sheet material

ABSTRACT

A method of grounding a dispenser. A low impedance path is connected to elements internal to the dispenser. The low impedance path is also connected to a surface contact spring which is adapted to contact an external mounting surface when the dispenser is affixed thereto. Static electrical charge accumulated on the elements is discharged through the low impedance path and the surface contact spring to the external mounting surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/185,172 filed Feb. 20, 2014, now U.S. Pat. No. 9,661,958, which is acontinuation of U.S. application Ser. No. 12/131,368 filed Jun. 2, 2008,now U.S. Pat. No. 8,684,297, which is a continuation of U.S. applicationSer. No. 11/329,766 filed Jan. 10, 2006, now U.S. Pat. No. 7,387,274,which is a continuation of U.S. application Ser. No. 10/807,988 filedMar. 23, 2004, now U.S. Pat. No. 7,017,856, which is a continuation ofU.S. application Ser. No. 09/966,124 filed Sep. 27, 2001, now U.S. Pat.No. 6,871,815, which is a continuation-in-part of U.S. application Ser.No. 09/780,733, filed Feb. 9, 2001, now U.S. Pat. No. 6,592,067. Thepriorities of the foregoing applications are hereby claimed and theentirety of their disclosures incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to the field of grounding for static electricitybuild-up in dispensing systems.

BACKGROUND

As is readily apparent, a long-standing problem is to keep paper towelavailable in a dispenser and at the same time use up each roll ascompletely as possible to avoid paper waste. As part of this system, oneought to keep in mind the person who refills the towel dispenser. Anoptimal solution would make it as easy as possible and as “fool-proof”as possible to operate the towel refill system and have it operate insuch a manner as the least amount of waste of paper towel occurs. Thiswaste may take the form of “stub” rolls of paper towel not being usedup.

Transfer devices are used on some roll towel dispensers as a means ofreducing waste and decreasing operating costs. These transfer deviceswork in a variety of ways. The more efficient of these devicesautomatically begin feeding from a reserve roll once the initial roll isexhausted. These devices eliminate the waste caused by a maintenanceperson when replacing small rolls with fresh rolls in an effort toprevent the dispenser from running out of paper. These transfer devices,however, tend to be difficult to load and/or to operate. Consequently,these transfer devices are less frequently used, even though they arepresent.

The current transfer bar mechanisms tend to require the maintenanceperson to remove any unwanted core tube(s), remove the initial partialroll from the reserve position, and position the initial partial rollinto the now vacant stub roll position. This procedure is relativelylong and difficult, partly because the stub roll positions in thesecurrent paper towel dispensers tend to be cramped and difficult to getto.

In order to keep a roll available in the dispenser, it is necessary toprovide for a refill before the roll is used up. This factor generallyrequires that a “refill” be done before the current paper towel roll isused up. If the person refilling the dispenser comes too late, the papertowel roll will be used up. If the refill occurs too soon, the amount ofpaper towel in the almost used-up roll, the “stub” roll, will be wastedunless there is a method and a mechanism for using up the stub roll eventhough the dispenser has been refilled. Another issue exists, as to theease in which the new refill roll is added to the paper towel dispenser.The goal is to bring “on-stream” the new refill roll as the last of thestub roll towel is being used up. If it is a task easily done by theperson replenishing the dispensers, then a higher probability existsthat the stub roll paper towel will actually be used up and also that arefill roll be placed into service before the stub roll has entirelybeen used up. It would be extremely desirable to have a paper toweldispenser which tended to minimize paper wastage by operating in anearly “fool proof” manner with respect to refilling and using up thestub roll.

As an enhancement and further development of a system for deliveringpaper towel to the end user in as cost effective manner and in auser-friendly manner as possible, an automatic means for dispensing thepaper towel is desirable, making it unnecessary for a user to physicallytouch a knob or a lever.

It has long been known that the insertion of an object with a dielectricconstant into a volume with an electrostatic field will tend to modifythe properties which the electrostatic field sees. For example,sometimes it is noticed that placing one hand near some radios willchange the tuning of that radio. In these cases, the property of thehand, a dielectric constant close to that of water, is enough to alterthe net capacitance of a tuned circuit within the radio, where thatcircuit affects the tuning of the RF signal being demodulated by thatradio. In 1973 Riechmann (U.S. Pat. No. 3,743,865) described a circuitwhich used two antenna structures to detect an intrusion in theeffective space of the antennae. Frequency and amplitude of a relaxationoscillator were affected by affecting the value of its timing capacitor.

The capacity (C) is defined as the charge (Q) stored on separatedconductors with a voltage (V) difference between the conductors:

C=Q/V.

For two infinite conductive planes with a charge per unit area of σ, aseparation of d, with a dielectric constant, of the material between theinfinite conductors, the capacitance of an area A is given by:

C=∈Aσ/d

Thus, where part of the separating material has a dielectric constant ∈₁and part of the material has the dielectric constant ∈₂, the netcapacity is:

C=∈ ₁ A ₁ σ/d+∈ ₂ A ₂ σ/d

The human body is about 70% water. The dielectric constant of water is7.18×10⁻¹⁰ farads/meter compared to the dielectric constant of air(STP): 8.85×10⁻¹² farads/meter. The dielectric constant of water is over80 times the dielectric constant of air. For a hand thrust into one partof space between the capacitor plates, occupying, for example, ahundredth of a detection region between large, but finite parallelconducting plates, a desirable detection ability in terms of the changein capacity is about 10⁻⁴ About 10⁻² is contributed by the difference inthe dielectric constants and about 10⁻² is contributed by the “area”difference.

Besides Riechmann (1973), other circuits have been used for, or could beused for proximity sensing.

An important aspect of a proximity detector circuit of this type is thatit be inexpensive, reliable, and easy to manufacture. A circuit made ofa few parts tends to help with reliability, cost and ease ofmanufacture. Another desirable characteristic for electronic circuits ofthis type is that they have a high degree of noise immunity, i.e., theywork well in an environment where there may be electromagnetic noise andinterference. Consequently a more noise-immune circuit will performbetter and it will have acceptable performance in more areas ofapplication.

The presence of static electric charges on a surface, which is inproximity to electronic systems, creates a vulnerability to the presenceof such charges and fields. Various approaches to grounding the surfacesare used to provide a pathway for the static electric charges to leavethat surface. Since static electric charges may build up from one or twokilovolts to 30 or more kilovolts in a paper-towel-dispensing machine,the deleterious effect on electronic components can be very real. Anapproach involves using an existing ground such as an AC ground “greenwire” in a three-wire 110-volt system. The grounding is achieved byattaching to the ground wire or conduit. The grounding wire isultimately connected to an earth ground. This approach is widely used inthe past and is well known. However, many locations where a motorizedpaper towel dispenser might be located do not have an existing AC systemwith ground.

In cases where grounded receptacles are not present, a ground may beproduced by driving a long metal rod, or rods, into the earth. Anothermethod for grounding utilizes a cold water pipe, which enters and runsunderground. Roberts (U.S. Pat. No. 4,885,428) shows a method ofgrounding which includes electrical grounding receptacles and insulatedground wire connected to a single grounding point, viz., a grounding rodsunk into the earth. This method of Roberts avoids grounding potentialdifferences. Otherwise grounding each grounding receptacle to a separategrounding rod likely finds in-ground variation of potential. Soilconditions such as moisture content, electrolyte composition and metalcontent are factors that can cause these local variations in groundingpotential. The cost and inconvenience of installing a grounding rodsystem may be prohibitive to support an installation of a motorizedpaper towel dispenser.

However, in many instances it may not be possible to have either ofthese approaches available. Therefore, a desirable grounding approachwould be to ground to a local surface, termed a local ground, which maybe a high impedance object, which is only remotely connected to an earthground. In particular, dispensing paper towels, and other materials, canproduce static electric build up charge during the dispensing cycle. Inthe past the static electricity build up, when it was produced on alever crank or pulled-and-tear type systems paper towel dispensers, hadlittle or no effect on the performance of the dispensing system. Themost that might happen would be the user receiving a “static-electricshock.” Although unpleasant this static electric shock is not injuriousto the person or to the towel dispenser.

Today, however, dispensing systems are often equipped with batteries.These batteries may operate a dispensing motor. However, in additionthere may other electronic circuitry present, for example, a proximitysensing circuit might utilize low power CMOS integrated circuits. TheseCMOS integrated circuits are particularly vulnerable to static electriccharge build up. It is desirable to protect these electronic from thestatic electric discharge.

In analyzing the static charge build up one may look at the chargeseparation occurring during a ripping operation of the towel or from theaction of the paper on rollers or other items in the dispensing pathway.

A ground may be regarded as a sink of charge. This sink may be large asin the case of an actual earth ground. On the other hand, this groundingmay relate to a relatively smaller sink of charge, a local ground. Thesink of charge may be a wall or a floor or a part of such objects. Thestatic charge build up may be in one sense regarded as a charge in acapacitor separated from a ground (as the second surface of thecapacitor) by a high impedance material. The charge can't reach an earthground as the wall material does not conduct electricity well.

There is, however, another mode of dispersing the charge on the surface.The isolated charges are of the same sign. The charges tend to repeleach other. Therefore, the tendency is to spread out on the surface.Where the surface is completely dry and of a non-conductive material,then the actual conduction is very low. The motion of the charges,whether electrons or positive or negative ions, may be impeded bysurface tension (Van der Waal) forces between the charges (electrons,negative ions or positive ions). Therefore, in the case where thesurface is somewhat damp, even at a low 5% to 10% relative humidity, itis likely that various impurities are present in the water so as to forma weak, conducting electrolyte solution. At higher humidity thisprovides for an even more efficient way of dispersing the charges on thesurface.

SUMMARY OF THE INVENTION

The present invention is directed toward a method of grounding adispenser to control the build-up of static electricity. A low impedancepath is connected to elements internal to the dispenser. The lowimpedance path is also connected to a surface contact spring which isadapted to contact an external surface to which the dispenser ismounted. Static electrical charge which accumulates on the internalelements of the dispenser is discharged through the low impedance pathand the contact spring to the external surface.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevation of the dispenser with the cover closed, withno internal mechanisms visible;

FIG. 2 is a perspective view of the dispenser with the cover closed,with no internal mechanisms visible;

FIG. 3 shows a view of the carousel support, the locking bar and thetransfer bar;

FIG. 4A is a perspective view of the of the dispenser with the carouseland transfer bar, fully loaded with a main roll and a stub roll;

FIG. 4B is a side view of the locking bar showing the placement of thecompression springs;

FIG. 4C shows the locking mechanism where the locking bar closest to therear of the casing is adapted to fit into a mating structure in the rearcasing;

FIG. 5 is a perspective, exploded view of the carousel assembly;

FIG. 6A is a side elevation view of the paper feeding from the stub rollwhile the tail of the main roll is positioned beneath the transfer bar;

FIG. 6B is a side elevation view of the stub roll is completelyexhausted, so that the transfer bar tucks the tail of the main roll intothe feed mechanism;

FIG. 7A is a side elevation view of the carousel ready for loading whenthe main roll reaches a specific diameter;

FIG. 7B is a side elevation view of the locking bar being pulledforwardly to allow the carousel to rotate 180°, placing the main roll inthe previous stub roll position;

FIG. 7C shows the location of the extension springs which tend tomaintain the transfer bar legs in contact with the stub roll;

FIG. 7D shows the cleanable floor of the dispenser;

FIG. 8A shows a schematic of the proximity circuit;

FIG. 8B (prior art) shows the schematic for the National Semiconductordual comparator LM393;

FIG. 9 shows the U1 waveforms at pin 1 (square wave A), pin 5(exponential waveform B) and pin 6 (exponential waveform C);

FIG. 10A is a perspective view of a paper towel dispenser with an accesshole for the grounding wire and shows a molded rib which prevents thelow impedance grounding wire from contacting an idler gear;

FIG. 10B is a perspective view a screw boss and molded ribs forattaching the wall contact spring grounding clip to the chassis of thedispenser;

FIG. 10C is another perspective view of the screw boss and ribs forattaching the wall contact spring grounding clip to the chassis;

FIG. 11A is a perspective view of the gear cover with a molded rib thatholds the spring contact in place;

FIG. 11B is a perspective view of the grounding wire contacting thespring clip and entering an access hole toward its other end;

FIG. 11C is a side elevational view of the towel dispenser showing thegrounding wire, the spring contact which connects to the grounding wireand also connects to the wall contact spring grounding clip;

FIG. 12 is a perspective view of the path of the grounding wire after itenters the access hole;

FIG. 13A is a rear, perspective view of the opening for the wall contactspring grounding clip of the towel dispenser;

FIG. 13B is a perspective view of the wall contact spring grounding clipin place in the back of the paper-towel-dispensing unit;

FIG. 14 is a perspective view of the static charge flow path includingthe nib roller to the nib roller shaft, the compression spring, thespring contact, and the grounding wire; and

FIG. 15 is an elevational view showing the compression spring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is merely made for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

An embodiment of the invention comprises a carousel-based dispensingsystem with a transfer bar for paper towels, which acts to minimizeactual wastage of paper towels. As an enhancement and furtherdevelopment of a system for delivering paper towel to the end user in acost effective manner and in as user-friendly manner as possible, anautomatic means for dispensing the paper towel is desirable, making itunnecessary for a user to physically touch a knob or a lever. Anelectronic proximity sensor is included as part of the paper toweldispenser. A person can approach the paper towel dispenser, extend hisor her hand, and have the proximity sensor detect the presence of thehand. The embodiment of the invention as shown here, is a system, whichadvantageously uses a minimal number of parts for both the mechanicalstructure and for the electronic unit. It has, therefore, an enhancedreliability and maintainability, both of which contribute to costeffectiveness.

An embodiment of the invention comprises a carousel-based dispensingsystem with a transfer bar for paper towels, which acts to minimizeactual wastage of paper towels. The transfer bar coupled with thecarousel system is easy to load by a service person; consequently itwill tend to be used, allowing stub rolls to be fully utilized. Insummary, the carousel assembly-transfer bar comprises two components, acarousel assembly and a transfer bar. The carousel rotates a used-upstub roll to an up position where it can easily be replaced with a fullroll. At the same time the former main roll which has been used up suchthat its diameter is less than some p inches, where p is a rationalnumber, is rotated down into the stub roll position. The tail of the newmain roll in the upper position is tucked under the “bar” part of thetransfer bar. As the stub roll is used up, the transfer bar moves downunder spring loading until the tail of the main roll is engaged betweenthe feed roller and the nib roller. The carousel assembly is symmetricalabout a horizontal axis. A locking bar is pulled out to unlock thecarousel assembly and allow it to rotate about its axis, and is thenreleased under its spring loading to again lock the carousel assembly inplace.

A side view, FIG. 1, of the dispenser 20 with the cover 22 in placeshows an upper circular bulge 24, providing room for a full roll ofpaper towel, installed in the upper position of the carousel. The shapeof the dispenser is such that the front cover tapers inwardly towardsthe bottom to provide a smaller dispenser volume at the bottom wherethere is a smaller stub roll of paper towel. The shape tends to minimizethe overall size of the dispenser. FIG. 2 shows a perspective view ofthe dispenser 20 with cover 22 in place and the circular (cylindrical)bulge 24, together with the sunrise-like setback 26 on the cover 22,which tends to visually guide a hand toward the pseudo-button 28,leading to activation of a proximity sensor (not shown). A lightemitting diode (LED) 130 is located centrally to the pseudo-button 28.The LED 130 (FIG. 3) serves as an indication that the dispenser 20 ison, and dispensing towel. The LED 130 may be off while the dispenser isnot dispensing. Alternatively, the LED 130 may be lit (on), and when thedispenser 20 is operating, the LED 130 might flash. The LED 130 mightshow green when the dispenser 20 is ready to dispense, and flashinggreen, or orange, when the dispenser 20 is operating to dispense. Anysimilar combination may be used. The least power consumption occurs whenthe LED 130 only lights during a dispensing duty cycle. The sunrise-likesetback 26 (FIG. 2) allows a hand to come more closely to the proximitysensor (not shown).

FIG. 3 shows the main elements of the carousel assembly 30. The carouselarms 32 have friction reducing rotating paper towel roll hubs 34, whichare disposed into the holes of a paper towel roll (66, 68, FIG. 4A). Thelocking bar 36 serves to lock and to release the carousel for rotationabout its axis 38. The locking bar 36 rides on one of the correspondingbars 40. The two corresponding bars 40 serve as support bars.Cross-members 42 serve as stiffeners for the carousel assembly 30, andalso serve as paper guides for the paper to be drawn over and down tothe feed roller 50 and out the dispenser 20. These cross members areattached in a rigid fashion to the corresponding bars 40 and in thisembodiment do not rotate.

The legs 46 of the transfer bar 44 do not rest against the frictionreducing rotating paper towel roll hubs 34 when there is no stub roll 68present but are disposed inward of the roll hubs 34. The bar part 88 ofthe transfer bar 44 will rest against a structure of the dispenser, forexample, the top of modular electronics unit 132, when no stub roll 68is present. The bar part 88 of the transfer bar 44 acts to bring thetail of a new main roll of paper towel 66 (FIG. 4A) down to the feedroller 50 which includes intermediate bosses 146 (FIG. 3) and shaft 144.The carousel assembly is disposed within the fixed casing 48. The coveris not shown.

Feed roller 50 serves to feed the paper towels 66, 68 (FIG. 4A) beingdispensed onto the curved dispensing ribs 52. The curved dispensing ribs52 are curved and have a low area of contact with the paper toweldispensed (not shown). If the dispenser 20 gets wet, the curveddispensing ribs 52 help in dispensing the paper towel to get dispensedby providing low friction and by holding the dispensing towel off of thewet surfaces it would otherwise contact.

The feed roller 50 is typically as wide as the paper roll, and includesdrive rollers 142 and intermediate bosses 146 on the drive shaft 144.The working drive rollers or drive bosses 142 (FIG. 3) are typically aninch or less in width, with intermediate bosses 146 (FIG. 3) locatedbetween them. Intermediate bosses 146 are slightly less in diameter thanthe drive rollers or drive bosses 142, having a diameter 0.015 to 0.045inches less than the drive rollers or drive bosses 142. In thisembodiment, the diameter of the intermediate bosses 146 is 0.030 inchesless than the drive roller 142. This configuration of drive rollers ordrive bosses 142 and intermediate bosses 146 tends to prevent thedispensing paper towel from becoming wrinkled as it passes through thedrive mechanism and reduces friction, requiring less power to operatethe feed roller 50.

A control unit 54 operates a motor 56. Batteries 58 supply power to themotor 56. A motor 56 may be positioned next to the batteries 58. A light60, for example, a light-emitting diode (LED), may be incorporated intoa low battery warning such that the light 60 turns on when the batteryvoltage is lower than a predetermined level.

The cover 22 of the dispenser is preferably transparent so that theamount of the main roll used (see below) may be inspected, but also sothat the battery low light 60 may easily be seen. Otherwise anindividual window on an opaque cover 22 would need to be provided toview the low battery light 60. Another approach might be to lead out thelight by way of a fiber optic light pipe to a transparent window in thecover 22.

In a waterproof version of the dispenser, a thin piece of foam rubberrope is disposed within a u-shaped groove of the tongue-in-groove matingsurfaces of the cover 22 and the casing 48. The dispensing shelf 62 is amodular component, which is removable from the dispenser 20. In thewaterproof version of the dispenser 20, the dispensing shelf 62 with themolded turning ribs 52 is removed. By removing the modular component,dispensing shelf 62, there is less likelihood of water being divertedinto the dispenser 20 by the dispensing shelf 62, acting as a funnel orchute should a water hose or spray be directed at the dispenser 20, bythe shelf and wetting the paper towel. The paper towel is dispensedstraight downward. A most likely need for a waterproof version of thedispenser is where a dispenser is located in an area subject to beingcleaned by being hosed down. The dispenser 20 has an on-off switch whichgoes to an off state when the cover 22 is pivoted downwardly. The actualswitch is located on the lower face of the nodule 54 and is not shown.

In one embodiment, the user may actuate the dispensing of a paper towelby placing a hand in the dispenser's field of sensitivity. There can beadjustable delay lengths between activations of the sensor.

There is another aspect of the presence of water on or near thedispenser 20. A proximity sensor (not visible) is more fully discussedbelow, including the details of its operation. However, as can beappreciated, the sensor detects changes of capacitance such as arecaused by the introduction of an object with a high dielectric constantrelative to air, such as water, as well as a hand which is about 70%water. An on-off switch 140 is provided which may be turned off beforehosing down and may be turned on manually, afterwards. The switch 140may also work such that it turns itself back on after a period of time,automatically. The switch 140 may operate in both modes, according tomode(s) chosen by the user.

A separate “jog” off-on switch 64 is provided so that a maintenanceperson can thread the paper towel 66 by holding a spring loaded jogswitch 64 which provides a temporary movement of the feed roller 50.

FIG. 4A shows the dispenser case 48 with the carousel assembly 30 andtransfer bar 44. The carousel assembly 30 is fully loaded with a mainroll 66 and a stub roll 68, both mounted on the carousel arms 32 torotate on the rotating reduced friction paper towel roll hubs 34 (onlyshown from the back of the carousel arms 32). In the carousel assembly30, the two carousel arms 32, joined by corresponding bars 40 and crossmembers 42, rotate in carousel fashion about a horizontal axis definedby the carousel assembly rotation hubs 38. The locking bar 36 issupported, or carried, by a corresponding bar 40. The corresponding bar40 provides structural rigidity and support. The locking bar 36principally serves as a locking mechanism. Each paper towel roll 66, 68has an inner cardboard tube which acts as a central winding coreelement, and which provides in a hole in paper towel roll 66, 68 at eachend for engaging the hubs 34.

FIG. 5 shows the carousel assembly 30 in exploded, perspective view. Thenumber of parts comprising this assembly is small. From a reliabilitypoint of view, the reliability is increased. From a manufacturing pointof view, the ease of manufacture is thereby increased and the cost ofmanufacture is reduced. The material of manufacture is not limitedexcept as to the requirements of cost, ease of manufacture, reliability,strength and other requirements imposed by the maker, demand.

When the main roll, 66 (FIG. 4A) and the stub roll 68, (FIG. 4A) are inplace, the carousel arms 32 are connected by these rolls 66 and 68 (FIG.4A). Placing cross-members 42 to connect the carousel arms 32 with thelocking 36 and corresponding 40 bar results in better structuralstability, with racking prevented. The locking bar 36, which was shownas a single unit locking bar 36 in the previous figures, acts as alocking bar 36 to lock the carousel assembly 30 in the properorientation. It acts also as the release bar, which when released,allows the carousel assembly 30 to rotate. Two compression springs 70,72 are utilized to center the locking bar 36.

FIG. 4B is a side view of the locking bar showing the placement of thecompression springs. The compression springs 70, 72 also tend to resistthe release of the locking bar 36, insuring that a required force isneeded to unlock the locking bar 36. The required force is typicallybetween 0.5 lbf and 3.0 lbf, or more. In this embodiment, the force is2.0 lbf when the spring in a fully compressed position, and 1.1 lbf whenthe spring is in the rest position. In the rest position, the forces ofthe opposing springs offset each other.

The actual locking occurs as shown in FIG. 4C. The locking bar 36closest to the rear of the casing 48 is adapted to fit into a generallyu-shaped mating structure 118 which is adapted to hold the locking bar36 and prevent it and the carousel assembly 30 from rotating. When thelocking bar 36 is pulled away from the rear of the casing 48, thelocking bar 36 is disengaged from the mating structure 118. The matingstructure has an upper “high” side 120 and a lower “low” side 122, wherethe low side has a “ramp” 124 on its lower side. As the locking bar 36is pulled out to clear the high side 120, the carousel assembly 30 isfree to rotate such that the top of the carousel assembly 30 rotates upand away from the back of the casing 48. As the carousel assembly 30begins to rotate, the user releases the locking bar 36 which, under theinfluence of symmetrically placed compression springs 70, 72 returns toits rest position. As the carousel assembly rotates, the end of thesymmetrical locking bar 36 which originally was disposed toward the usernow rotates and contacts the ramp 124. A locking bar spring, e.g., 70 or72, is compressed as the end of the locking bar 36 contacting the ramp124 now moves up the ramp 124. The end of the locking bar 36 is pressedinto the space between the low side 122 and the high side 120, as theend of the locking bar 36 slides past the low side 122. A lockedposition for the carousel assembly 30 is now reestablished.

FIG. 5 shows the carousel arms 32 adapted to receive the loading of anew roll of towel 66 (FIG. 4A). The arms 32 are slightly flexible andbent outward a small amount when inserting a paper towel roll 66 (FIG.4A) between two opposite carousel arms 32. A friction reducing rotatingpaper towel roll hub 34 is inserted into a hole of a paper towel roll 66(FIG. 4A), such that one roll hub 34 is inserted into a hole on eachside of the paper towel roll 66 (FIG. 4A). Also shown in FIG. 5 are thetamper resistant fasteners 74, which attach the friction-reducingrotating paper towel roll hubs 34 to the carousel arms 32.

FIG. 5 shows the surface 76 of the roll hubs 34 and the surface 78 ofthe carousel arms 66, which contact each other. These contact surfaces76, 78 may be made of a more frictionless material than that of whichthe carousel arms 32 and the roll hubs 34 are made. For example, aplastic such as polytetrafluoroethylene (PTFE), e.g., TEFLON®, may beused, as a thin layer on each of the contacting surfaces. The papertowel dispenser 20 and its components may be made of, including but notlimited to, plastic, metal, an organic material which may include but isnot limited to wood, cardboard, treated or untreated, a combination ofthese materials, and other materials for batteries, paint, if any, andwaterproofing.

FIG. 6A shows the paper 80 feeding from the stub roll 68 while the tail82 of the main roll 66 is positioned beneath the transfer bar 44. Thelegs (visible leg 46, other leg not shown) of the transfer bar 44 restsagainst the stub roll. When the diameter of the stub roll 68 is largerby a number of winds of paper towel than the inner roll 84, the legs 46of the transfer bar 44 dispose the bar 88 of the transfer bar 44 to berotated upward from the feed roller 50.

FIG. 6B shows the situation where the stub roll 68 is exhausted, so thatthe transfer bar 44 tucks the tail 82 of the main roll 66 into the feedmechanism 86. FIG. 6B shows the stub roll 68 position empty, as the stubroll has been used up. The stub roll core 84 is still in place. As thestub roll 68 is used up, the legs 46 of the transfer bar 44 move uptoward the stub roll core (inner roll) 84, and the bar 88 of thetransfer bar is disposed downward toward the feed roller 50 and towardthe top of a structural unit of the dispenser 20 (FIG. 2), such as thetop of the electronics module 132 (FIG. 3). Initially the main roll 66is in reserve, and its tail 82 in an “idling” position such that it isunder the transfer bar 44. The main roll 66 and its tail 82 are notinitially in a “drive” position. However, as the stub roll 68 is usedup, the downward motion of the bar transfer bar, 44 driven by its springloading, brings the bar 88 of the transfer bar 44 down to engage themain roll tail 82 with the feed roller 50.

FIG. 7A shows the carousel assembly 30 ready for loading when the mainroll 66 reaches a specific diameter. The diameter of the main roll 66may be measured by comparison of that diameter with the widened “ear”shape 122 (FIG. 4A) on each end of the carousel arms 32. That part ofeach carousel arm 32 is made to measure a critical diameter of a mainroll 66. The carousel assembly 30 is tilted forward when it is locked.The carousel assembly 30 may rotate unassisted after the locking bar 36is released, due to the top-heavy nature of the top roll. That is, thetorque produced by the gravitational pull on the main-roll 66 is largerthan that needed to overcome friction and the counter-torque produced bythe now empty stub roll 68.

FIG. 7B shows the process of loading where the service person pulls thelocking bar 36 and allows the carousel to rotate 180°, placing the mainroll 66 in the previous stub roll 68 position. Now a new full sized roll66 can be loaded onto the main roll 66 position. The transfer bar 44automatically resets itself. The transfer bar 44 is spring loaded so asto be disposed with the transfer bar legs 46 pressed upward against thestub roll 68 or the stub roll core 84. The transfer bar legs 46 areadapted to be disposed inward of the roll hubs 34 so the bar 88 of thetransfer bar 44 will have a positive stop at a more rigid location, inthis case, the top of the electronics module 132 (FIG. 2).

FIG. 7C shows the extension springs 126, 128 which tend to maintain thetransfer bar legs 46 in contact with the stub roll 68 or stub roll core84. The transfer bar 44 contains the two extension springs 126, 128. Thespring forces are typically 0.05 lbf to 0.5 lbf in the bar 44 loweredposition and 0.2 lbf to 1.0 lbf in the bar 44 raised position. In thisembodiment, the spring forces are 0.2 lbf in the lowered position and0.43 lbf in the raised position. The force of the two springs 126, 128is additive so that the transfer bar 44 is subject to a total springforce of 0.4 lbf in the lowered position and 0.86 lbf in the raisedposition.

While modular units (FIG. 7D) such as the electronics module 132, themotor 56 module, and the battery case 150, are removable, they fit, or“snap” together so that the top of the electronics unit 132, the top ofthe motor 56 module and remaining elements of the “floor” 148 of thedispensing unit 20 form a smooth, cleanable surface. Paper dust anddebris tend to accumulate on the floor 148 of the dispenser 20. It isimportant that the dispenser 20 is able to be easily cleaned as part ofthe maintenance procedure. A quick wiping with a damp cloth will sweepout and pick up any undesirable accumulation. The removable modulardispensing shelf 64 may be removed for rinsing or wiping.

The feed roller 50 may be driven by a motor 56 which in turn may bedriven by a battery or batteries 58, driven off a 100 or 220V AC hookup,or driven off a transformer which is run off an AC circuit. Thebatteries may be non-rechargeable or rechargeable. Rechargeablebatteries may include, but not be limited to, lithium ion, metalhydride, metal-air, nonmetal-air. The rechargeable batteries may berecharged by, but not limited to, AC electromagnetic induction or lightenergy using photocells.

A feed roller 50 serves to feed the paper towel being dispensed onto thecurved dispensing ribs 52. A gear train (not visible) may be placedunder housing 86 (FIG. 3) for driving the feed roller. A control unit 54(FIG. 3) for a motor 56 (FIG. 3) may be utilized. A proximity sensor(not shown) or a hand-operated switch 64 may serve to turn the motor 56on and off.

As an enhancement and further development of a system for deliveringpaper towel to the end user in as cost effective manner anduser-friendly manner as possible, an automatic means for dispensing thepaper towel is desirable, making it unnecessary for a user to physicallytouch a knob or a lever. Therefore, a more hygienic dispenser ispresent. This dispenser will contribute to less transfer of matter,whether dirt or bacteria, from one user to the next. The results ofwashing ones hands will tend to be preserved and hygiene increased.

An electronic proximity sensor is included as part of the paper toweldispenser. A person can approach the paper towel dispenser, extend hisor her hand, and have the proximity sensor detect the presence of thehand. Upon detection of the hand, a motor is energized which dispensesthe paper towel. It has long been known that the insertion of an objectwith a dielectric constant into a volume with an electromagnetic fieldwill tend to modify the properties, which the electromagnetic fieldsees. The property of the hand, a dielectric constant close to that ofwater, is enough to alter the net capacitance of a suitable detectorcircuit.

An embodiment of the invention comprises a balanced bridge circuit. SeeFIG. 8A. The component U1A 90 is a comparator (TLC3702 158) configuredas an oscillator. The frequency of oscillation of this component, U1A90, of the circuit may be considered arbitrary and non-critical, as faras the operation of the circuit is concerned. The period of theoscillator is set by the elements C_(ref) 92, R_(hys) 94, the trimresistance, R_(trim) 96, where the trim resistance may be varied and therange resistors R_(range) 152 are fixed. The resistors R_(range) 152allow limits to be placed on the range of adjustment, resulting in aneasier adjustment. The adjustment band is narrowed, since only part ofthe total resistance there can be varied. Consequently a singlepotentiometer may be used, simplifying the adjustment of R_(trim) 96. Avalue for R_(range) 152 for the schematic shown in FIG. 8A might be 100kΩ. R_(trim) 96 might have an adjustment range of 10 kΩ to 50 kΩ. Theoutput signal at pin 1 98 of component U1A 90 is a square wave, as shownat line A of FIG. 9. C_(ref) 92 is charged by the output along with ANT100, both sustaining the oscillation and measuring the capacitance ofthe adjacent free space. The signals resulting from the charging actionare applied to a second comparator, U1B 102, at pin 5 104 and pin 6 106(FIG. 8A). These signals appear as exponential waveforms, as shown atlines B and C of FIG. 9.

The simplest form of a comparator is a high-gain differential amplifier,made either with transistors or with an op-amp. The op-amp goes intopositive or negative saturation according to the difference of the inputvoltages because the voltage gain is typically larger than 100,000, theinputs will have to be equal to within a fraction of a millivolt inorder for the output not to be completely saturated. Although anordinary op-amp can be used as comparator, there are special integratedcircuits intended for this use. These include the LM306, LM311, LM393154 (FIG. 8A), LM393V, NE627 and TLC3702 158. The LM393V is a lowervoltage derivative of the LM393 154. The LM393 154 is an integratedcircuit containing two comparators. The TLC3702 158 is a micropower dualcomparitor with CMOS push-pull 156 outputs. FIG. 8B (prior art) is aschematic which shows the different output structures for the LM393 andthe TLC3702. The dedicated comparators are much faster than the ordinaryop-amps.

The output signal at pin 1 98 of component U1A 90, e.g., a TL3702 158,is a square wave, as shown in FIG. 8A. Two waveforms are generated atthe inputs of the second comparator, U2B 102. The first comparator 90 isrunning as an oscillator producing a square-wave clocking signal, whichis input, to the clock input of the flip-flop U2A 108, which may be, forexample, a Motorola D flip-flop, No. 14013.

Running the first comparator as a Schmitt trigger oscillator, the firstcomparator U1A 90 is setup to have positive feedback to thenon-inverting input, terminal 3 110. The positive feedback insures arapid output transition, regardless of the speed of the input waveform.R_(hys) 94 is chosen to produce the required hysteresis, together withthe bias resistors R_(bias1) 112 and R_(bias2) 114. When these two biasresistors, R_(bias1) 112, R_(bias2) 114 and the hysteresis resistor,R_(hys) 94, are equal, the resulting threshold levels are ⅓ V+ and ⅔ V+,where V+158 is the supply voltage. The actual values are not especiallycritical, except that the three resistors R_(bias1) 112, R_(bias2) 114and R_(hys) 94, should be equal, for proper balance. The value of 294 kΩmay be used for these three resistors, in the schematic shown in FIG.8A.

An external pull-up resistor, R_(pullup1) 116, which may have a value,for example, of 47052, is only necessary if an open collector comparatorsuch as an LM393 154 is used. That comparator 154 acts as anopen-collector output with a ground-coupled emitter. For low powerconsumption, better performance is achieved with a CMOS comparator,e.g., TLC3702, which utilizes a CMOS push-pull output 156. The signal atterminal 3 110 of U1 A charges a capacitor C_(ref) 92 and also chargesan ANT sensor 100 with a capacitance which C_(ref) 92 is designed toapproximate. A value for C_(ref) for the schematic of FIG. 8A, for themost current board design, upon which it depends, is about 10 pF. As theclocking square wave is effectively integrated by C_(ref) 92 and thecapacitance of ANT 100, two exponential signals appear at terminals 5104 and 6 106 of the second comparator U1B, through the R_(protect) 160static protection resistors. R_(protect) 160 resistors provide limitingresistance which enhances the inherent static protection of a comparitorinput lines, particularly for the case of pin 5 104 of U1B 102. In theschematic shown in FIG. 8A, a typical value for R_(protect) 160 might be2 kΩ. One of the two exponential waveforms will be greater, dependingupon the settings of the adjustable resistance R_(trim) 96, C_(ref) 92,and ANT 100. The comparator U1B 102 resolves small differences,reporting logic levels at its output, pin 7 118. As the waveforms mayinitially be set up, based on a capacitance at ANT 100 of a givenamount. However, upon the intrusion of a hand, for example, into thedetection field of the antenna ANT 100, the capacitance of ANT 100 isincreased significantly and the prior relationship of the waveforms,which were set with ANT 100 with a lower capacitance, are switched over.Therefore, the logic level output at pin 7 118 is changed and the Dflip-flop 108 state is changed via the input on pin 5 of the D flip-flop108.

The second comparator 102 provides a digital quality signal to the Dflip-flop 108. The D flip-flop, U2A 108, latches and holds the output ofthe comparator U1B 90. In this manner, the second comparator is reallydoing analog-to-digital conversion. A suitable D flip-flop is a Motorola14013.

The presence, and then the absence, of a hand can be used to start amotorized mechanism on a paper towel dispenser, for example. Anembodiment of the proximity detector uses a single wire or a combinationof wire and copper foil tape that is shaped to form a detection field.This system is very tolerant of non-conductive items, such as papertowels, placed in the field. A hand is conductive and attached to a muchlarger conductor to free space. Bringing a hand near the antenna servesto increase the antenna's apparent capacitance to free space, forcingdetection.

The shape and placement of the proximity detector's antenna (FIG. 8A,100) turns out to be of some importance in making the proximity sensorwork correctly. Experimentation showed that a suitable location wastoward the lower front of the dispenser unit. The antenna (FIG. 8A, 100)was run about two-thirds the length of the dispensing unit, in amodular, replaceable unit above the removable dispensing shelf 62 (FIG.3). This modular unit would be denoted on FIG. 3 as 120.

A detection by the proximity detection circuit (FIG. 8A) in the module120 sets up a motor control flip flop so that the removal of the handwill trigger the start of the motor cycle. The end of the cycle isdetected by means of a limit switch which, when closed, causes a resetof the flip-flop and stops the motor. A cycle may also be initiated byclosing a manual switch.

A wide range of sensitivity can be obtained by varying the geometry ofthe antenna and coordinating the reference capacitor. Small antennaehave short ranges suitable for non-contact pushbuttons. A large antennacould be disposed as a doorway-sized people detector. Another factor insensitivity is the element applied as R_(trim). If R_(trim) 96 isreplaced by an adjustable inductor, the exponential signals becomeresonant signals with phase characteristics very strongly influenced bycapacitive changes. Accordingly, trimming with inductors may be used toincrease range and sensitivity. Finally, circuitry may be added to theantenna 100 to improve range and directionality. As a class, thesecircuits are termed “guards” or “guarding electrodes,” old in the art, atype of shield driven at equal potential to the antenna. Equal potentialinsures no charge exchange, effectively blinding the guarded area of theantenna rendering it directional.

The antenna design and trimming arrangement for the paper toweldispenser application is chosen for adequate range and minimum cost. Theadvantages of using a guarded antenna and an adjustable inductor arethat the sensing unit to be made smaller.

From a safety standpoint, the circuit is designed so that a detectionwill hold the motor control flip-flop in reset, thereby stopping themechanism. The cycle can then begin again after detection ends.

The dispenser has additional switches on the control module 54. FIG. 3shows a “length-of-towel-to-dispense-at-one-time” (‘length”) switch 134.This switch 134, is important in controlling how long a length of papertowel is dispensed, for each dispensation of towel. It is an importantsetting for the owner of the dispenser on a day-to-day basis indetermining cost (to the owner) versus the comfort (to the user) ofgetting a large piece of paper towel at one time.

A somewhat similar second switch 136 is“time-delay-before-can-activate-the-dispensing-of another-paper-towel”(“time-delay”) switch 136. The longer the time delay is set, the lesslikely a user will wait for many multiple towels to dispense. This tendsto save costs to the owner. Shortening the delay tends to be morecomfortable to a user.

A third switch 138 is the sensitivity setting for the detection circuit.This sensitivity setting varies the resistance of R_(trim) 96 (FIG. 8A).Once an effective antenna 100 (FIG. 8A) configuration is set up, thedistance from the dispenser may be varied. Typical actual use mayrequire a sensitivity distance out to one or two inches, rather thanfour or six inches. This is to avoid unwanted dispensing of paper towel.In a hospital setting, or physician's office, the sensitivity settingmight be made fairly low so as to avoid unwanted paper towel dispensing.At a particular work location, on the other hand, the sensitivity mightbe set fairly high, so that paper towel will be dispensed very easily.

While it is well known in the art how to make these switches accordingto the desired functionality, this switch triad may increase theusefulness of the embodiment of this invention. The system, as shown inthe embodiment herein, has properties of lowering costs, improvinghygiene, improving ease of operation and ease of maintenance. Thisembodiment of the invention is designed to consume low power, compatiblewith a battery or battery pack operation. In this embodiment, a 6 voltDC supply is utilized. A battery eliminator may be use for continuousoperation in a fixed location. There is a passive battery supply monitorthat will turn on an LED indicator if the input voltage falls below aspecified voltage.

The most spectacular example of a build-up of static electric chargecaused by mechanical separation of charge is the giant thunderstorm,with violent displays of lightning and the associated thunder. A morequiet but more pernicious static buildup problem is that associated withthe destruction of electronic integrated circuit chips by unwantedstatic discharge to susceptible circuit leads. A common occurrence ofthe discharge of a mechanically-caused static charge buildup happenswhen a person becomes charged-up walking on a rug on a dry, typicallycold, day and has an unpleasant but non-injurious experience ofdischarging that charge by contacting a grounded object.

A similar situation occurs on a paper towel dispenser. Here, however,the separation of charge tends to be caused as a paper towel isseparated from the main roll by being ripped-off along a guide bar, or asmooth or serrated blade. Some mechanical charge separation may alsooccur from the action of the paper towel web sliding alongrib-structures and rollers of the dispenser. In many places where apaper towel dispenser is placed there is no, or no convenient access, toa ground wire or conduit of a 110V or 220 V electrical supply system orgrounding rods or other ground-to-earth conductor.

Consequently, the approach of this invention is used instead. To groundstatic electricity buildup on a paper towel dispenser, a highconductivity grounding wire connects internal components of thedispenser that are subject to accumulating static electric charge. Thehigh conductivity grounding wire connects to an electrical mechanicalcontact on the outside of the dispenser. A metal contact between thehigh conductivity pathway, and for example, the wall against which thedispenser is mounted, provides an electrical pathway for the dissipationof the static electrical build up on the dispenser to a local electricalground.

The first step is to provide a low impedance pathway for collecting thestatic electric charge on the dispenser and bringing it to a wallcontact. FIG. 10A shows a side of a paper towel dispenser 2002 with anaccess hole 2004 for the grounding wire (not shown) and shows a moldedrib 2006 which prevents the low impedance grounding wire (not shown)from contacting an idler gear. The idler gear is not shown. This rib2006 may be molded into the structure. The rib helps to route thegrounding wire out of the way of a potentially interfering mechanism.The grounding wire 2016 may be seen in FIG. 11B. The access holeprovides a convenient entrance so as to allow the routing of the lowimpedance grounding wire to the rear wall contact.

Features of the chassis structure provide an approach to securing boththe grounding wire 2016 (FIGS. 11B, 11C, 14) to the rear wall contact2020 (FIGS. 11C, 12, 13B) and securing the metal wall contact 2020 tothe chassis of the dispenser. For the wall contact (not shown) there isa screw 2008 (FIG. 10C) and ribs 2010 (FIG. 10C) for attaching the wallcontact to the chassis. This is seen in FIG. 10B and in a different viewfrom FIG. 10C. The wall contact may be screwed to the chassis and thegrounding wire secured to the wall contact with the same screw.

Since the nib rollers tend to pick up the initial static electriccharge, the grounding wire is run from the nib rollers to the wallcontact. Thus FIG. 11A shows the gear cover 2012 with a rib 2014 moldedinto it, which holds the spring clip 2018 (FIGS. 11C, 12, 13B) in place.Keeping the grounding wire in a relatively straight line from the chargecollection near the charge generation source allows a minimum length forthe grounding wire 2016 (FIGS. 11B, 11C).

The actual contacting is of the grounding wire 2016 to a spring clip2018, by a spring clip attachment means (2026, FIG. 11C). The spring hasa spring clip means as part of its structure. FIG. 11B shows thegrounding wire 2016 and its connection to the spring clip 2018 (FIGS.11C, 12, 13B). A compression spring 2019 (FIG. 15) contacts the metalnib roller shaft (2022, FIG. 14) by spring pressure, providing amechanical and electrical contact. The static electricity accumulated onthe nib rollers may transfer from the nib rollers to the metal nibroller shaft (2022, FIGS. 11B, 11C, 14). Then the static electricity maytransfer through the spring clip 2018 to the grounding wire 2016. Theground wire 2016 is held by a spring clip means (2026, FIG. 14) to thespring clip 2018 (FIGS. 11C, 12, 13B).

FIG. 12 is a perspective view showing the wall contact spring groundingclip 2020 and the ground wire 2016, which is partially hidden as itenters the access hole 2004. The wall contact spring grounding clip 2020is on the rear side of the paper towel dispenser. It is connected to thegrounding wire 2016, which is hidden by part of the structure of thedispenser 2002. In FIG. 11C, toward the front side of the dispenser2002, the grounding wire 2016 is connected to the spring clip 2018 thatelectrically and mechanically connects to the nib roller shaft 2022 byspring pressure. As FIG. 11C shows, the grounding contact runs from thenib roller (not shown) to the metal nib roller shaft 2022 through aspring clip 2018 (FIGS. 11C, 12, 13B). The ground contact continuesthrough the grounding wire 2016 to the wall contact spring groundingclip 2020. When the dispenser 2002 is mounted on a wall, the wallcontact spring grounding clip 2020, acting as a partially compressedspring, presses against the wall to maintain a mechanical pressurecontact which provides an electrical conduction path to the wall fromthe static build up areas on the towel dispenser 2002.

FIG. 12 shows the pathway of the grounding wire 2016 from where itenters the access hole 2004 toward the interior of the dispenser 2002.The grounding wire 2016 continues until it contacts the wall contactspring grounding clip 2020. The ground wire 2016 is attached to the wallcontact spring grounding clip 2020 by screw, bolt, soldering or othercommon methods of affixing a grounding wire to a metal contact whichserves to complete a grounding path.

It may be appreciated that a dispenser may be made of alternativematerials or combinations of materials. For example, in the case wherethe rear chassis of the dispenser is made of galvanized steel orstainless steel, the chassis itself may be formed with one or moreintegral spring wall contacts. The grounding wire, in these embodiments,may be attached by a means including, but not limited to, screw, bolt,soldering, brazing, or welding. In another embodiment, the rear chassismay be of a plastic, but having metal straps. These metal straps mayalso be formed with one or more integral spring contacts. The groundingwire may then be attached to the metal straps. Again, the dispenser maybe made completely of metal, for example, stainless steel. In thisembodiment, the grounding wire system may be used, or, the electricalgrounding path may be from the spring contact, which presses against thenib roller, to the metal paper towel dispenser casing to the rear wall,by way of one or more integral spring wall contacts.

FIG. 13A shows the opening 2026 in the rear cover 2028 for the wallcontact spring grounding clip. The placement of the opening tends to bedetermined by keeping a shortest grounding wire, together withstructural manufacturing considerations for the paper towel dispenserchassis.

FIG. 13B shows the wall contact spring grounding clip 2020 in place,ready for the paper towel dispensing unit 2002 to be mounted in such away as to press that wall contact spring grounding clip against the walland maintain a good mechanical and electrical contact.

FIGS. 14 and 15 illustrate the dispenser 2002 with the front coverremoved, shows further details of the connection from the nib roller(not shown) to the metal nib roller shaft 2022 and then through a springclip 2018 which connects to the nib roller compression spring (notshown) and a spring clip attachment means 2026 connected to thegrounding wire 2016 and to the wall contact spring grounding (not shown)clip to the wall (not shown).

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A dispenser for dispensing flexible sheetmaterial, comprising: a support adapted to hold a roll of flexible sheetmaterial; a cover adapted to move from a closed position covering theroll to an open position allowing access to the roll; a motor drivenfeed mechanism adapted to receive and dispense flexible sheet materialfrom the roll; an electronic proximity sensor adapted to detect thepresence of a user; an electronic control unit in operable communicationwith the electronic proximity sensor and the motor driven feed mechanismand adapted to control dispensation of the flexible sheet material, theelectronic control unit comprising a jog off-on switch adapted toprovide movement of the motor driven feed mechanism upon depression ofthe jog off-on switch.
 2. The dispenser of claim 1, wherein the jogoff-on switch is adapted to provide temporary movement of the motordriven feed mechanism while the jog off-on switch is maintained in adepressed state.
 3. The dispenser of claim 1, wherein the jog off-onswitch is adapted to allow the flexible sheet material to be threadedthrough the motor driven feed mechanism while the jog off-on switch ismaintained in a depressed state.
 4. The dispenser of claim 1, whereinthe cover covers the jog off-on switch when the cover is in the closedposition, and wherein the cover allows access to the jog off-on switchwhen the cover is in the open position.
 5. The dispenser of claim 1,wherein the electronic control unit further comprises an on-off switchadapted to move from an on position when the cover is in the closedposition to an off position when the cover is in the open position. 6.The dispenser of claim 1, wherein the electronic control unit furthercomprises a length switch adapted to control a length of the flexiblesheet material being dispensed by the motor driven feed mechanism. 7.The dispenser of claim 6, wherein the cover covers the length switchwhen the cover is in the closed position, and wherein the cover allowsaccess to the length switch when the cover is in the open position. 8.The dispenser of claim 1, wherein the electronic control unit furthercomprises a time delay switch adapted to set a time delay betweensuccessive dispense cycles of the flexible sheet material beingdispensed by the motor driven feed mechanism.
 9. The dispenser of claim8, wherein the cover covers the time delay switch when the cover is inthe closed position, and wherein the cover allows access to the timedelay switch when the cover is in the open position.
 10. The dispenserof claim 1, wherein the electronic control unit further comprises asensitivity switch adapted to control a sensitivity of the electronicproximity sensor.
 11. The dispenser of claim 10, wherein the covercovers the sensitivity switch when the cover is in the closed position,and wherein the cover allows access to the sensitivity switch when thecover is in the open position.
 12. A dispenser for dispensing flexiblesheet material, comprising: a support adapted to hold a roll of flexiblesheet material; a motor driven feed mechanism adapted to receive anddispense flexible sheet material from the roll; an electronic proximitysensor adapted to detect the presence of a user; an electronic controlunit in operable communication with the electronic proximity sensor andthe motor driven feed mechanism and adapted to control dispensation ofthe flexible sheet material, the electronic control unit comprising asensitivity switch adapted to control a sensitivity of the electronicproximity sensor, and a jog off-on switch adapted to provide movement ofthe motor driven feed mechanism upon depression of the jog off-onswitch; and a cover adapted to move from a closed position to an openposition, wherein the cover covers the sensitivity switch when the coveris in the closed position, and wherein the cover allows access to thesensitivity switch when the cover is in the open position.
 13. Thedispenser of claim 12, wherein the electronic control unit furthercomprises a length switch adapted to control a length of the flexiblesheet material being dispensed by the motor driven feed mechanism. 14.The dispenser of claim 13, wherein the cover covers the length switchwhen the cover is in the closed position, and wherein the cover allowsaccess to the length switch when the cover is in the open position. 15.The dispenser of claim 12, wherein the electronic control unit furthercomprises a time delay switch adapted to set a time delay betweensuccessive dispense cycles of the flexible sheet material beingdispensed by the motor driven feed mechanism.
 16. The dispenser of claim15, wherein the cover covers the time delay switch when the cover is inthe closed position, and wherein the cover allows access to the timedelay switch when the cover is in the open position.
 17. The dispenserof claim 12, wherein the jog off-on switch is adapted to providetemporary movement of the motor driven feed mechanism while the jogoff-on switch is maintained in a depressed state.
 18. The dispenser ofclaim 12, wherein the jog off-on switch is adapted to allow the flexiblesheet material to be threaded through the motor driven feed mechanismwhile the jog off-on switch is maintained in a depressed state.
 19. Thedispenser of claim 12, wherein the cover covers the jog off-on switchwhen the cover is in the closed position, and wherein the cover allowsaccess to the jog off-on switch when the cover is in the open position.